Enable swapping a frame back in to its parent process

content/browser/frame_host/render_frame_host_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_manager.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 914 matching lines @@
   // If there is no last non-interstitial entry (and current_instance already
   // has a site), then we must have been opened from another tab.  We want
   // to compare against the URL of the page that opened us, but we can't
   // get to it directly.  The best we can do is check against the site of
   // the SiteInstance.  This will be correct when we intercept links and
   // script-based navigations, but for now, it could place some pages in a
   // new process unnecessarily.  We should only hit this case if a page tries
   // to open a new tab to an interstitial-inducing URL, and then navigates
   // the page to a different same-site URL.  (This seems very unlikely in
   // practice.)
-  const GURL& current_url = (current_entry) ? current_entry->GetURL() :
+  const GURL& current_url = (current_entry) ? frame_tree_node_->current_url() :

[Charlie Reis, 2014/10/28 16:38:29]

I'm a little nervous about this because I don't trust
frame_tree_node_->current_url() as much as current_entry->GetURL().  I think
they should be the same (for main frames), though, and I can see that this is
needed for subframes until we get FrameNavigationEntries.

It's independent of the rest of this CL, so let's split it out into a different
CL with a CHECK_EQ of the two URLs in the main frame case, just to give
confidence that there's no behavior change there.  (Otherwise this is a
dangerous place to introduce regressions.)

[Nate Chapin, 2014/10/28 19:59:19]

Ok, will split out and land that first.

       current_instance->GetSiteURL();
 
   // View-source URLs must use a new SiteInstance and BrowsingInstance.
   // We don't need a swap when going from view-source to a debug URL like
   // chrome://crash, however.
   // TODO(creis): Refactor this method so this duplicated code isn't needed.
   // See http://crbug.com/123007.
   if (current_entry &&
       current_entry->IsViewSourceMode() != dest_is_view_source_mode &&
       !IsRendererDebugURL(dest_url)) {
@@ skipping 661 matching lines @@
 void RenderFrameHostManager::DeleteRenderFrameProxyHost(
     SiteInstance* instance) {
   RenderFrameProxyHostMap::iterator iter = proxy_hosts_.find(instance->GetId());
   if (iter != proxy_hosts_.end()) {
     delete iter->second;
     proxy_hosts_.erase(iter);
   }
 }
 
 }  // namespace content